Crime Scene Processing
"Crime scene management, and evidence management as a critical part of that, must be learned and incorporated into the investigator`s toolkit"
Introduction
Crime scene processing involves a series of 6 key steps that act as a strategy by which evidence can be collected, documented, and preserved for future use in legal proceedings- This systematic approach ensures that the maximum amount of evidence can be recovered from the scene.
The order of the steps taken can differ depending on the type of crime that has occurred and it`s environment, however the underlying goal of maximising the evidence and it`s integrity for court is still crucial.
"85% of crime scene evidence can be compromised within the first hour of discovery"
What are these steps?
1) Initial Assessment
2) Secure/Cordon
3) Coordinate/Plan
4) Primary Survey
5) Evidence Collection
6) Secondary Survey
1) Initial Assessment
Preserve Life
Immediately upon reaching the crime scene, the preservation of life must occur. Treating any injured persons is paramount before any steps can be taken to recover and preserve evidence from the scene. Some evidence may be lost during this, however, it is crucial to save lives and treat injuries whenever possible at a scene.
Liaise
After authorised healthcare personnel have left the scene, the Crime Scene Investigator can then liaise with the First Officer Attending, the Officer In Charge, witnesses, etc, to gather as much information as possible. This includes the nature of the incident, the name of the injured party, and access and egress routes taken by victims/suspects.
What Is Required
By collating information from the OIC, FOA, and witnesses, it gives clarity on what is required from the scene examination, enabling the Investigator`s to begin planning how to proceed with examination.
2) Secure/Cordon
"Every contact leaves a trace", Locard`s Principle.
It is vital when processing a crime scene to follow this principle throughout, hence the many actions put in place to reduce cross-contamination.
Once the focal point (main area of disturbance) has been identified, cordons are erected in a large space surrounding it. The area cordoned off is always bigger than required to ensure that it contains all possible relevant evidence, as it is far easier to narrow down the scene than to expand it later on.
There are 2 types of cordons - The inner and the outer:
- The inner cordon is only available to authorised personnel and protects the immediate scene.
- The outer cordon is available to both authorised personnel and necessary first responders, and cordons off a large area around the immediate scene.
A Common Approach Path is also used to reduce contamination of the scene. A CAP is the route that every personnel entering/leaving the scene takes. It leads from the cordons, to the focal point and this path must be cleared of evidence first. It is crucial that the CAP is away from the path taken by the offender as this may also contain significant evidence, e.g. footwear marks.
Stepping plates can also be used throughout the scene as a way to minimise any possible risk of damaging evidence by stepping on it accidentally.
3) Coordinate/Plan
Once all cross-contamination measures have been taken, a final plan can be made for the order which evidence should be collected. This can depend on many variables, I.E. Is the scene indoors/outdoors. If the scene was outdoors, then it would be sensible to recover fibres first as they are most vulnerable to being blown away by wind, for instance.
The scene can also be split into different quadrants for individual examination, as this increases the opportunity for all possible evidence to definitely be recovered and noticed by the CSI`s.
4) Primary Survey
Locating Potential Evidence
A systematic visual examination of the scene now takes place. This is where any potential evidence is noted down for later collection, photographed, and sketches are made. The notes made can include information on any observations and conditions of the scene for later use.
Photography
Overall, mid-range, and close-range images are taken of the scene, and each piece of evidence to be collected. It aids in visualising the scene for future use by acting as a permanent record of the scene at the time.
Sketches
Sketches can be brief but must include the relevant facts of the scene. This ranges from the positioning of the victim and evidence location, relative to the rest of the scene. It should also include measurements to provide clear spatial dimensions in the scene.
5) Evidence Collection
Evidence from the scene must be collected based off the evidence collection strategy previously established. The proper procedures for evidence collection must be followed so that the opportunity for evidence to be damaged or contaminated is significantly reduced.
Different types of evidence are packaged and recovered differently. Fibres/hairs, for example, are retrieved using tweezers, whereas fingerprints are recovered using specific powder, such as metallic powder.
The way evidence is stored also differs - E.g. Sharp objects need to be stored in a plastic, puncture resistant tube.
What remains consistent throughout evidence collection however, is that all appropriate PPE must be worn, each evidence should be packaged individually in their own Tamper Evident Bag, and all must be correctly signed and dated, and contain a description of the item, date of collection, and the case number.
6) Secondary Survey
Once all evidence has been collected, a final walkthrough of the crime scene occurs. The primary goal of this is to ensure that no evidence has been missed or overlooked, and to finalise documentation and notes made throughout the examination process.
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